1. Field of the Invention
The present invention concerns an endoscopy capsule of the type that is magnetically navigable inside a patient, in particular his gastrointestinal tract. The endoscopy capsule (designed with an induction coil) has a magnetic dipole element for the navigation, which interacts with a magnetic field that is generated by a coil system at least partially surrounding the body of the patient. As used herein, navigation of the endoscopy capsule is both the translational movement as well as rotation and tilting of the capsule.
2. Description of the Prior Art
Minimally-invasive and non-invasive medical techniques are used and developed ever more frequently for examination and treatment of a person or animal as a patient. The use of endoscopes which are introduced into the patient via body orifices or small incisions has been typical for a long time. Inspection or manipulation devices (for example a camera or a grabber) to execute a desired action are located at the tip of a more or less long, flexible catheter. These can be used only to a limited extent due to friction effects and the limited length and flexibility of endoscopes.
A wirelessly operating device for endoscopy is known from DE 101 42 253. A device known as an “endorobot” in the form of an endoscopy capsule of approximately 2 cm length and approximately 1 cm diameter contains an inspection, diagnosis or therapy device. For example, this can be a video camera, a biopsy probe, a clip or a medicine reservoir. The capsule contains a magnetic element with a magnetic dipole moment, for example a permanent magnet. The capsule is moved wirelessly in the patient. For this purpose, the patient lies entirely or partially in an electrical coil system composed of multiple (for example fourteen) individual coils. Suitable gradient magnetic fields and magnetic fields, which generate corresponding forces for a translational movement and rotation moments for a rotation and tilt movement at the capsule located in the patient, are generated by the coil system in order to navigate the capsule in the patient in this manner. Since the rotation moments and forces acting on the capsule result from the product of the magnetic dipole moment and the magnetic field strength, namely the magnetic field gradient at the location of the capsule, it is advantageous to integrate as large a magnetic element as possible into the capsule in order to obtain sufficiently high rotation moments or forces. As an alternative, the magnetic field or the magnetic field gradient would have to be increased. However, this leads to very high power consumption and accompanying losses in the coil system since the ohmic power loss increases with the square of the magnetic field or magnetic field gradients to be generated.
In addition to a magnetic element with magnetic dipole moment, such an endoscopy capsule normally contains electrically conductive and/or ferromagnetic objects such as, for example, a battery or an induction coil with a ferrite core. With given external dimensions of the endoscopy capsule, the arrangement of the cited parts in the endoscopy capsule must be selected as advantageously as possible so that the electrically conductive and/or ferromagnetic objects in the endoscopy capsule do not attenuate the magnetic dipole field relevant for the magnetic navigation. Moreover, it is desirable that the magnetic element does not interfere with the adjacent objects or even impairs their function.